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Kirkham Motorsports

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  • 1 Post By eschaider
  • 1 Post By KarlzEE Bebout
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  • 1 Post By undy
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  #1 (permalink)  
Old 08-10-2023, 02:19 PM
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Default Ford 9 inch rear axle oil.

My Daytona with a 9 inch rear axle (not limited slip diff) might have a noisy axle. I say might because the car is very noisy anyway and because the rear end is very rigid with rose jointed suspension I’m thinking resonance might be an explanation. So you might be asking why I’m bothered? Well I’m not too bothered, ear plugs might be a solution, but thought if I filled the axle with oil that is most likely to quiet it then that’s the best I can do then put up with it. If I’m not mistaken and I stand to be corrected standard oil is EP90. An oil specialist here in the U.K. can offer a dual EP 70w/140 or a straight EP140. Thoughts please? Thanks.
Dek
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Old 08-10-2023, 04:43 PM
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If you are running a cruising or highway ratio like 2.92, 3.08 up to 3.55, the EP90 will work fine for you. If you have a 3.73 or deeper R&P, say, 3.90, 4.56, or?, then you will benefit from the EP140 lubes

Most 9” Ford pumpkins normally run whisper-quiet if they are set up properly. If they are not, no amount of lube is going to fix the problem. Pumpkins have specific fluid levels necessary for proper lubrication and cooling. Exceeding those design specs will typically not do anything good for you. If you have sufficiently overfilled the pumpkin, then normal operation will cause the oil to foam and usually come out of the breather.

If the noise is coming from the ring and pinion, then it is time for a new R&P. If it is coming from a wheel bearing, then it is time for a new wheel bearing. If it is coming from a damaged spline in its corresponding side gear, then it is time for a new axle and, most likely, a new side gear.
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Last edited by eschaider; 08-13-2023 at 03:32 PM.. Reason: Typed EP70 and should have typed EP90
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Old 08-13-2023, 01:27 PM
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Thanks for your reply Ed and sorry for the delay in responding. Did it earlier then got a text and when I got back it had disappeared into the ether. Firstly I must ask what a pumpkin is? I think this might be a case of two nations separated by a common language?
From what you say a different grade of oil won’t make the diff quieter. I’m pretty sure it’s not a wheel bearing noise or spline. I thought a higher viscosity oil whilst obviously not curing a wear problem might alleviate the noise from it. As far as use is concerned here in the U.K. on congested pot hold roads any “cruising” is only achieved on motorways in the early hours of the morning with the risk of speeding fines from overhead gantry cameras. Ggrrhh!
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Old 08-13-2023, 01:44 PM
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Forgot to address the ratio. I’ve got no idea quite frankly. Anyone know if there is identification stamped on the casing and where to look? I know it can be worked out on the car but this is way beyond my pay grade. It’s got a Tremec 5 speed and has fairly long legs. About 35mph per 1000rpm in top gear.
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Old 08-13-2023, 03:08 PM
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Dek, it's unlikely that your differential will have a gear ration identification. Raise your rear end after blocking the front tires. Put the transmission in neutral. Make a mark on the propeller shaft and one on the inside of one of the tires. Count how many times the propeller shaft rotates during one rotation of the tire. The number of shaft rotations will pretty accurately tell you your differential ratio. EEZY PEEZY
If you do find that you need some rebuild/repair work on the differential, that would be a prime time to install some sort of positraction. Years ago I used a "Powertrax" unit that was easy to install (did it myself) and really did the job. It has no clutches so there will sometimes be a click or snap when turning while backing up. Not an issue, just different. The Powertrax was still in the car, 50,000 miles later with no issues. I'd dome lots of drag racing, turning 10.7 seconds in the quarter mile, after driving 75 miles to the track, and then driving home. My 2¢ worth.
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Old 08-13-2023, 03:35 PM
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Quote:
Originally Posted by Daytona Dek View Post
Thanks for your reply Ed and sorry for the delay in responding. Did it earlier then got a text and when I got back it had disappeared into the ether. Firstly I must ask what a pumpkin is? I think this might be a case of two nations separated by a common language?
From what you say a different grade of oil won’t make the diff quieter. I’m pretty sure it’s not a wheel bearing noise or spline. I thought a higher viscosity oil whilst obviously not curing a wear problem might alleviate the noise from it. As far as use is concerned here in the U.K. on congested pot hold roads any “cruising” is only achieved on motorways in the early hours of the morning with the risk of speeding fines from overhead gantry cameras. Ggrrhh!
Dek

Dek,

Pumpkin is a colloquialism in this country for the removable 9" Ford center section containing the ring gear, pinion gear, and gear carrier. Apologies for the ambiguity; it was not intended.

When the noise comes from the ring and pinion, it is caused by improper installation. No amount or type of lube will silence this. The ring and pinion must be replaced with a known good (usually new) ring and pinion and then properly installed. The noise you are hearing comes from a mechanical interference between the incorrectly installed ring and pinion gears. The mechanical interference physically damages the gears such that they can never be reinstalled to produce a silent running rear axle.


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You need one of those new-fangled 100KW radar/camera detectors off the dark web. It scans continuously for a threatening device. When it finds one, it locks onto it and zaps it with a 100KW laser blast reducing the electronics and other stuff to a smoldering pile of rubble before the device can see you!
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Last edited by eschaider; 08-13-2023 at 06:00 PM.. Reason: Spelling & Grammar
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Old 08-13-2023, 07:17 PM
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Quote:
Originally Posted by KarlzEE Bebout View Post
Years ago I used a "Powertrax" unit that was easy to install (did it myself) and really did the job. It has no clutches so there will sometimes be a click or snap when turning while backing up. Not an issue, just different. The Powertrax was still in the car, 50,000 miles later with no issues. I'd dome lots of drag racing, turning 10.7 seconds in the quarter mile, after driving 75 miles to the track, and then driving home. My 2¢ worth.
No drag racing here, but also running the Powertrax Grip Pro. I installed it myself as well, without the benefit of a dial indicator. Paid a LOT of attention to backlash and tooth pattern. No problems after 7 years of use so I must have done okay. Highly recommended, IMO.

https://www.powertrax.com/product-in...action-system/
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Old 08-14-2023, 01:53 AM
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Quote:
Originally Posted by KarlzEE Bebout View Post
Dek, it's unlikely that your differential will have a gear ration identification. Raise your rear end after blocking the front tires. Put the transmission in neutral. Make a mark on the propeller shaft and one on the inside of one of the tires. Count how many times the propeller shaft rotates during one rotation of the tire. The number of shaft rotations will pretty accurately tell you your differential ratio. EEZY PEEZY
If you do find that you need some rebuild/repair work on the differential, that would be a prime time to install some sort of positraction. Years ago I used a "Powertrax" unit that was easy to install (did it myself) and really did the job. It has no clutches so there will sometimes be a click or snap when turning while backing up. Not an issue, just different. The Powertrax was still in the car, 50,000 miles later with no issues. I'd dome lots of drag racing, turning 10.7 seconds in the quarter mile, after driving 75 miles to the track, and then driving home. My 2¢ worth.
Thanks KarlzEE for explaining the method for determining the ratio. It’s not difficult but don’t suppose it’s sensitive enough to determine all the ratios outlined in Ed’s reply. Certainly would be able to differentiate between say 3 or 4 though.
Thanks again.
Dek
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Old 08-14-2023, 03:53 AM
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Why guess on what's making the noise? Put the rear axle up on jack stands. Have a friend start the car and put it in gear. Underneath it with a mechanic's stethoscope check the center section, axle bearings, etc.
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Old 08-14-2023, 06:41 AM
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Why guess on what's making the noise? Put the rear axle up on jack stands. Have a friend start the car and put it in gear. Underneath it with a mechanic's stethoscope check the center section, axle bearings, etc.
Had thought of this but don’t really fancy the idea of the car on axle stands with someone in it taking it through the gears at different revs with the rear wheels spinning inches from my head! Funny how you get more cautious as you get older. Probably would have had it on bricks when I was younger.
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Old 08-14-2023, 07:24 AM
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Dek, You'll be able to get pretty close to what the ratio is just by eye-balling the shaft revolutions: 3 1/4=3.23, 3 1/2=3.50, 3 3/4=3.73 etc.

Cycleguy, As I remember, I didn't have to remove the pinion so the lash to the ring gear was not affected. Anyway, it was a darn good unit and the pricing is very reasonable. $350 (=-) at Summit. Hard to beat if you're willing to but up with the clicks. The first time was a bit unnerving.
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Old 08-14-2023, 08:03 AM
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This could be any one of the rearends bearings or the gears.
I suggest you pay a mechanic for a diagnosis and repair estimate.

We remove the wheels and listen for noise.
Use a 4-5 foot tube to your ear, don’t climb under.
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Last edited by sunman; 08-14-2023 at 08:16 AM..
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Old 08-14-2023, 08:47 AM
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Dek,

You might get lucky and find it is some obscure, inexpensive, and easy to correct problem, but then again, it is much more likely that you won't! We don't get the easy or inexpensive solutions falling into our laps very often.

For the noise to be loud enough to be audible over your pipes and then loud enough to become an irritant, there are only two things that can do that. One is a bad carrier (or pinion) bearing, and the other is an improperly installed ring and pinion.

When you disassemble the rear end to remove the ring and pinion, it is a walk in the park to check the bearings. If they pass muster, then it is time for a new ring and pinion. It is really that simple.

All of the, it might be this, or it might be that BS, is a form of intellectual problem obfuscation. You attempt to convince yourself it is not as bad as you know it really is. Don't waste your time on the mental masturbation; fix the problem. After all, that was the original reason you embarked on this journey of pain and suffering.

This one has no easy or cheap way out other than do nothing and tolerate the noise until something breaks.
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Old 08-14-2023, 09:17 AM
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It could be a bad U-joint or axel bearing.
Ring gear to pinion play check by feeling it by hand.
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Old 08-14-2023, 12:53 PM
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I replaced my 9" rear with a unit built and supplied by Currie 3.73. It made a howling noise when in between accelerating and decelerating, kinda like coasting. I did put a heavier oil in it and it helped a lot. Years later I went to a 3.50 ratio and the mechanic shop who specializes in rear ends used Richmond gears and said they Richmond used to be noisy but now they are quiet. I dont hear that howling anymore so assuming Currie sets up their center sections correctly, I believe some gear manufacturers make better quality or maybe tend to have a quieter mesh.

John
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Old 08-14-2023, 02:10 PM
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Quote:
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Dek,

You might get lucky and find it is some obscure, inexpensive, and easy to correct problem, but then again, it is much more likely that you won't! We don't get the easy or inexpensive solutions falling into our laps very often.

For the noise to be loud enough to be audible over your pipes and then loud enough to become an irritant, there are only two things that can do that. One is a bad carrier (or pinion) bearing, and the other is an improperly installed ring and pinion.

When you disassemble the rear end to remove the ring and pinion, it is a walk in the park to check the bearings. If they pass muster, then it is time for a new ring and pinion. It is really that simple.



All of the, it might be this, or it might be that BS, is a form of intellectual problem obfuscation. You attempt to convince yourself it is not as bad as you know it really is. Don't waste your time on the mental masturbation; fix the problem. After all, that was the original reason you embarked on this journey of pain and suffering.


This one has no easy or cheap way out other than do nothing and tolerate the noise until something breaks.
Ed you hit so many nails on the head there. Mental masturbation-I can’t get that phrase out of my head now!
Dek
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Old 08-14-2023, 02:17 PM
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I replaced my 9" rear with a unit built and supplied by Currie 3.73. It made a howling noise when in between accelerating and decelerating, kinda like coasting. I did put a heavier oil in it and it helped a lot. Years later I went to a 3.50 ratio and the mechanic shop who specializes in rear ends used Richmond gears and said they Richmond used to be noisy but now they are quiet. I dont hear that howling anymore so assuming Currie sets up their center sections correctly, I believe some gear manufacturers make better quality or maybe tend to have a quieter mesh.

John
Yes the noise is a bit like that. Present on the over run. Interesting that the heavier oil helped which is where my post started. Thanks John.
Dek
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